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**jacks****Member**- Registered: 2012-11-21
- Posts: 80

A six faced fair dice is thrown until 1 comes, then the probability that 1 comes in even no. of trials is

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 87,237

Hi jacks;

I am getting

So the probability is 5 / 11.

This agrees with computer simulations.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

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**jacks****Member**- Registered: 2012-11-21
- Posts: 80

Thanks bobbym

would you like to explain it to me

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 87,237

Hi;

It is based on a tree and trick for summing series like that. What part do you need help on?

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

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